replacing a c-4 fuel pump

I went to start my 1996 corvette this morning and the engine would spin over just fine but not fire,
a quick check list ,run down of the potential reasons very quickly led me to the fact the fuel pump,
was not turning on, a few further verification's proved it was getting the electrical current required,it was NOT a RELAY, WIRE or CONNECTION,problem OR FUSE
its only about 3 years old and a BOSCH pump so I'm not too thrilled at the prospect of having to spend cash I don,t really have on hand either.

DeatschWerks DW300 340lph In-Tank Fuel Pump 1990-1996 Chevrolet Corvette 5.7L
so I'm probably going too order one of these DeatschWerks-DW300-340lph pumps, (linked below) just to get it up and running for now as it looks like it should function, in the application and its about the least expensive pump I think Id trust to do so.

I could get a stock replacement pump from rockauto for about $80

I could get a stock replacement pump AND ASSEMBLY from rockauto for about $260

but they would never keep up with the engines needs

the problem with all decent quality fuel line supply component parts is they cost more money, than the cheap low quality parts and generally take up more room and take a bit more time and thought to install correctly, but you tend to get what you pay for in car part quality, and carefully matched parts will significantly increase flow volume, and stabilize the pressure.
you NEED a high quality ,return line style, fuel pressure regulator
HLY-12-841_xla.jpg ... d_sbs_sg_1








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now Ive installed several dozen c4 corvette fuel pumps over the years so the complete lack of instructions coming with the replacement fuel pump is a major P.I.T.A. in my opinion.
you start by removing the gas filler plate by unscrewing the 4 torx t-15 screws on the gas tank flip top fill cover plate
T-15 Torq Screwdriver
youll need a 1/4" drive 10mm socket & ratchet with a 12" extension and a 3/8" wide flat blade screw driver and pliers for the fuel line clamps,the basic process is not difficult, consult the shop manual and ideally disconnect the battery cables for safety concerns while working on the fuel system, to remove the bolts and clamps after you work out the rubber spill guard plate



it came with the fuel filter sock. the tank gasket, the mount bolts
the pump came with gaskets,the filter socks held to the pump with a star crimp on stud locking fastener, the sock needs to be carefully placed and aligned and you really DO need two large cable tye-wraps that were not included,
to lock the pump securely in place, and hold the rubber vibration/noise wrap in place plus reduce any tendency of the pump from working its way loose from the filter sock over time due to vibration, but I think most experienced corvette mechanics know the drill by now (that a few seconds spent adding security cable ties, reduces noise and loose connections, and pumps coming loose from filter socks or fuel lines)


this pictures not an exact replica but a similar kit
and if you have never installed a c4 corvette fuel pump the lack of detailed instructions is going to be a major handi-cap

the only issue I had was the old existing filler neck rubber shroud seal thing I have was old and it ripped due to me being careless during its removal, and the wiring was a P.I.T.A, to remove and reconnect ,connecting it was easy enough but it was a real P.I.T.A. to disconnect without breaking the old brittle plastic connectors but they eventually went on and worked fine.
yes you can order a new splash guard rubber thing from ecklers corvettes or some other source for $25




step one pull trouble codes

L98/ TPI Engine Start Sequence
When you start an L-98 engine Corvette, a series of events take place that causes the engine to run. Knowing the sequence will help you troubleshoot no start conditions.

Fuel Rail Pressurization:

When you first turn the key to the “on” position, the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Shraeder valve on the passenger side fuel rail near the rear of the engine and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running.

Initial Crank Action:

If you then rotate the key to the start position (assuming the anti-theft system has not disabled the starter), the engine will rotate.

Once the oil pressure has reached 4 PSI, the oil pressure switch will close allowing the fuel pump to run. (Note that you should have a black oil pressure switch/sender. It is mounted behind the distributor on the driver’s side and if it is not black, it is suspect due to a run of bad units that stayed in the GM parts pipeline for some time).

The distributor will send a string of pulses to the ECM (Engine Control Module) in response to the engine being rotated by the starter. These pulses continue as long as the engine turns (both starting and running) and if they are not present, the engine will not run.

ECM Reaction:

If the ECM sees oil pressure greater than 4 PSI and the reference pulses from the distributor, it will energize the injector drivers which will begin pulsing the injectors on for 4 ms (milliseconds) periods. (In the L98, all injectors on one side of the engine fire at the same time followed by all injectors on the other side firing at the same time. On the LT-1, the injectors are fired individually at the appropriate time).

The ECM will also pull in the fuel pump relay in effect paralleling it electrically with the oil pressure switch. (If the fuel pump relay fails, you can still normally get the car to start and run unless you can’t make at least 4 PSI oil pressure. This is a “limp home mode” feature put in place to allow for a fuel pump relay failure).

The ECM also monitors the TPS (Throttle Position Sensor mounted on the throttle body assembly) and wants to see .54 volts at this time. If it sees appreciably more than 0.54 volts, it will assume the engine is flooded and the driver has pressed the accelerator to the floor to clear the flooded condition and restrict the fuel flow as a result. (.54 volts during start and at idle from the TPS is very important to both starting and run performance.)

Assuming the ignition module is good (meaning there is a spark of sufficient intensity to ignite the fuel), the engine will “catch”.

Engine "Catches":

When the engine catches, the MAF (Mass Air Flow sensor mounted just ahead of the throttle body) sends a signal to the ECM advising that air is flowing and also just how much air is being pulled through to the intake manifold. The ECM takes note of the amount of air being consumed and adjusts the injector pulse width to around 2.2 ms nominally so as to attain a proper air/fuel mixture to insure combustion. (This is how the 1985 through 1989 L-98 works. For information on the 1990 and 1991 L-98 variant, see the Note below).

The engine should show an initial idle speed of around 900-1100 RPM and then slowly diminish to 600-700 RPM unless the air conditioner is on in which case it will run at around 800 RPM.

If this does not happen, the Idle Air Mixture valve (located on the throttle body) may be misadjusted. Alternatively, there may be a leak in the intake manifold or another vacuum leak may be present. Listen for hissing sounds---there should be none.

ECM Mode:

The engine will now be in Open Loop mode meaning that the ECM is controlling the air/fuel mixture by referencing values stored in memory.

Once the Oxygen sensor (mounted on the exhaust pipe) reaches operating temperature of several hundred degrees, the Manifold Air Temperature (MAT) sensor shows an intake air temperature of more than 140 degrees and the Engine Coolant Temperature (ECT) has reached 160 degrees, the computer will switch to closed loop mode meaning the Oxygen sensor’s output is examined along with the MAT and ECT outputs and the ECM adjusts the injector pulse widths (more “on time” or less “on time”) to constantly strive for a 14.7:1 air/fuel mixture which is the best mixture to hold down pollution.

Note that prolonged idling can force the computer back into open loop mode.

Note: In 1990, the MAF was eliminated from the engine in favor of a speed/density system. This system uses a sensor called the MAP sensor which measures the Manifold Absolute Pressure (hence the name MAP) and compares it with the atmospheric pressure outside the intake manifold. This information, coupled with the Manifold Air Temperature, Engine Coolant Temperature and Engine RPM is used by the ECM to determine the amount of air entering the cylinders. It is a different way of reaching the desired 14.7:1 air-fuel mixture ratio but functionally is like the MAF system in that the ECM uses the feedback to control the "on time" for the injectors.

Corvette used this approach in the 1990 and 1991 L-98 engines and in the 1992 and 1993 LT-1 engines. With the 1994 model C4, they went back to the MAF system. Note that MAF based systems are far more accurate since they measure air flow directly whereas the MAP system infers air flow indirectly. A multitude of things can throw the calculation off and Corvette returned to the MAF system beginning with the 1994 C4 (with a MAP backup). From a troubleshooting standpoint, the MAP operation comes into the sequence the same place that the MAF does.


If you have a no start condition or if the L-98 starts and then dies, check the above items in sequence to see if all the events are occurring as required.

A Scan Tool makes this job much easier and is a highly recommended troubleshooting aid for these sorts of problems.
youll find a hour or so reading thru the links and sub links, on this site in the threads, will provide a great wealth of related info and incite into related factors, or the function or testing of sensors, that you may not currently be thinking about, or things that you might not think that are related to your issue that PROBABLY ARE

without testing your simply guessing
C4 Sensor Check Information
first check your shop manual for the fuse and fuse able link locations
fuses are located in several locations and fuse-able links near the battery

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Fuel Line Pinch
I've had my 93 for a month or so now, and it appears a previous owner pinched the return fuel line when jacking.

The car runs fine, but I don't have a fuel pressure gauge on it.

I'm wondering how laborious is it to change the fuel line? I know where I can get a pre bent stainless line and if i'm doing one, may as well do both. But I can't find information on changing just the fuel lines. They snake around pretty heavily in the back so i'm not sure what all needs to come off the car to get them in place.

The other option is to cut the pinch out and replace it with rubber fuel line.


Ive replaced both the fuel lines in several c4 corvettes and its certainly something you can do on jack stands or a lift, in a few hours if your familiar with doing similar projects, yes the fuel tank needs to be dropped, but my first question has got to be

.. if it runs fine currently and your not having issues why are you changing it?
if your concerned put a fuel pressure gauge on the shrader valve

and rev the engine a few times and watch the fuel pressure it should in theory remain in the 38 psi-42 psi range

'92+ LT1 & LT4 Fuel.jpg[from]=&price[to]=&year=1996&make=Chevrolet&v_model=Corvette&cab=&ton=&duty=&drive=&box=&engine=&ymm_cat=Fuel Supply Line
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Id agree a belt driven fuel pumps, or direct drive off the cam drive, like I used on my Crower / kinsler stack injection
for my big block 1968 race corvette is and was far superior to the skimpy electric pumps, but at over $1000 for the pump and fittings it is not cheap
Best way to install an electric fuel pump for EFI is to install it inside the FUEL CELL OR gas tank. There are MANY reasons to do this:
2. An electric pump pushes fuel much more EFFICIENTLY than it sucks fuel
3. INSTALLING BOTH A RETURN STYLE FUEL PRESSURE REGULATOR AND AN INTAKE FUEL PUMP,allows you to run a return LINE THAT EMPTY'S FUEL BACK INTO THE TANK which keeps the fuel lines cooler and greatly reduces any tendency too vapor lock in a carburetor equipped engine by constantly circulating fresh fuel through the lines and back to the tank.
4. It allows a much more efficient turbine impeller style of fuel pump, which increases pressure and volume of the pump.



Your Website search Engine for Hilborn Belt Drive Fuel Pumps took me right to here Grumpy.
Our last conversation back in 2014 on it.
well we might get some traffic at least as a result:D
I am Looking for the Drive Spud or a Full Drive Mandrel off the front of the Crankshaft Harmonic Balancer for a Pontiac V8.
Not sure how it was done exact back in the day.
Or its done today on a Pontiac V8.

I think only Big Chief from Street Outlaws with his Crow GTO has a Belt drive fuel pump.
Race fuel cell is mounted up front.
Seen pictures on Facebook.
Most of Facebook is not Google searchable.
I did Google Image search.
Found 1 picture.
Get it uploaded.
Not a very good pic.
Found it Grumpy.

The Bolaws Belt drive fuel pump I have is universal. Need the correct drive mandrel.
Mine uses the Gimore Belt. Have 2 .
Also work with my TCI Rattler Pontiac V8 racing balancer.
Still using them on Engine Master Vids you posted recent.
Yes i also think it was axial and also check litres to gallons regardless. and i also for thanks for this excellent information.
I recently tried to start my 1996 corvette, it failed to start, diagnoses led to finding the fuel pump was not running due to corrasion.
the connections to the pump wiring had simply vanished, there were no pins or sockets left, corrosion
on the connection wiring that had just rusted to powder, and the fuel tank fill level sensor badly rusted, this is partly my fault as I let the 1996 corvette sit for almost a year, once I moved to texas ,with a full tank of ETHANOL LACED fuel, I had added a quart of MMO and two full cans of
STABIL marine fuel stabilizer, to the tank and then I took a 10 minute drive to let it mix with the fuel in the tank and fuel lines, when I left FLA, erroneously thinking that would prevent corrosion issues,
now I know any ethanol laced fuel must be replaced if the cars sitting in storage


marine STABIL helps but its not a 100% long term cure for damage that might be the result of old fuel sitting in your car's fuel tank

I drained the tank, it looked like it was full of COCA-COLA, not fuel but the tank itself looked ok

so I order the parts required to make the repairs



the filler neck boot had a rip in it so that also gets replaced
one of the few really nice things about owning a corvette , is that there's a huge parts support industry,
and you may pay through the nose to get everything you want if you
select the better quality parts
but at least they are readily available even if your corvette is 50-60 years old,
something that's not true on many older, less popular muscle cars
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yes they sell bigger fuel pumps for your c4 corvette yet I must point out a fact here
you don't need more than a 340 lph fuel pump as in theory that pump supposts 650-700 HP

The AEM 340LPH High Flow In-Tank Fuel Pump (PN 50-1000) flows 340 lph (84 gph) at 40 PSI
and is capable of supporting over 650 HP at 43 PSI. yes if you have extra cash there's always someone willing to sell you parts you can't really use.
larger capacity fuel pumps require higher amp relays, larger fuses thicker ga wiring and bigger fuel lines to maximize flow rates

convert gph to liters per hour - Google Search
then theres less expensive options

I gallon per hour (GPH)= 3.78541 (LPH)
1 liter per hour ( LPH )= 0.264172 gallons per hour (GPH)

yes theres also cheaper options on a c4 corvette fuel pump
but if you want the corvette to run at its best selecting cheaper parts is rarely the best option
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I ordered the required repair parts, and they came today, the mounting bracket, with the fuel tank level sensor and wiring for the pump and the pump showed up, I'm still waiting on the filler neck rubber gasket, the electrical plug connectors that came with the pump won't fit the mounting bracket electrical plugs or fuel level sensor connections, and the mounting bracket electrical connections won,t fit the pump wiring, now obviously there's only three wires and I can cut and splice,solder and use some heat shrink tube insulators thus getting things correctly wired up, very easily , to get all the plugs and connectors to work, on both the bracket and pump, but still its a P.I.T.A.
Im lucky I did not throw the old pump bracket assembly away as its helpful in showing the correct wire connections
, if I just blindly matched the color of the wires on both of the components it would never work
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